Composition for bonded magnet, bonded magnet, and integrally molded member

By adjusting the ratio of samarium-iron-nitrogen-based magnet powder, carbon fiber, carboxylic acid ester and polyamide resin in the bonded magnet composition, and adding a specific polyamide elastomer, the contradiction between fluidity and durability in the prior art is solved, and high fluidity and excellent hot and cold impact test durability are achieved.

CN120019452APending Publication Date: 2025-05-16SUMITOMO METAL MINING CO LTD +1
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Patent Information

Application Number
CN202380071602.3
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Priority Date
2022-12-14
Filing Date
2023-12-13
Publication Date
2025-05-16

AI Technical Summary

Technical Problem

When the conventional bonding magnet composition improves fluidity, it is difficult to maintain durability and adhesiveness to hot and cold impact tests.

Method used

The fluidity of the bonded magnet composition is improved by combining a specific samarium-iron-nitrogen-based magnet powder, carbon fibers, carboxylic acid ester and polyamide resin in a predetermined proportion, and adding a specific polyamide elastomer.

Benefits of technology

It is realized that while maintaining durability and adhesion to hot and cold impact tests, the fluidity of the bonded magnet composition is improved, and is suitable for miniaturization and high-characterization electronic equipment.

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Abstract

Provided is a composition for a bonded magnet, which maintains durability and adhesiveness with respect to a thermal shock test, and which has higher fluidity than conventional compositions. Also provided are: a bonded magnet which is a molded body of the composition for bonded magnets; and an integrally molded member provided with the bonded magnet. The bonded magnet composition contains a samarium-iron-nitrogen magnet powder having an average particle diameter of 1.7 [mu] m to 2.8 [mu] m in a proportion of 88.0 mass% to 91.0 mass%, and a polyamide elastomer having a tensile elongation at break of 400% or more and a flexural modulus of 70 MPa or more in a proportion of 3.0 mass% to 7.0 mass%. The present invention is characterized by containing 0.5-2.0 mass% of carbon fibers having a fiber diameter of 5-12 [mu] m (inclusive), 0.3-1.0 mass% of a carboxylic acid ester (inclusive), and 1.0-8.0 mass% of a polyamide 12 resin having a weight-average molecular weight (Mw) in a molecular weight distribution measurement of 4500-7500 (inclusive). The composition for bonded magnets has a fluidity of 1.5 cm3 / sec or more as measured using a flow tester under conditions of a capillary temperature of 250 DEG C, a load of 588 N, an orifice diameter of 1 mm, an orifice length of 1 mm, and a warm-up time of 300 sec.
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Citation Information

Patent Citations

  • Preparation of heat-shrinkable sheet

    JP1984079733A